The present invention relates to a semiconductor package and method of packaging a tape ball grid array (TBGA) package, e.g., an integrated circuit, and more particularly to a TBGA package wherein an anodized aluminum frame is used to serve the dual purpose of supporting the tape automated bonding (TAB) substrate during assembly and dissipating heat generated by the integrated circuit chip in the semiconductor package.
In the last few decades, the electronics industry has literally transformed the world. Electronic products are used by, or affect the daily lives of, a large segment of the world's population. For example, telephones, television, radios, Personal Computers (PCS), laptop PCS, palmtop PCS, PCS with built-in portable phones, cellular phones, wireless phones, pagers, modems, and video camcorders, are just a few of the electronic products that have been developed in recent years and which have been made smaller and more compact, while providing more and/or enhanced functions than ever before. The integrated circuit (IC) chip, and the more efficient packaging of the IC chip, have played a key role in the success of these products.
The IC chip, sometimes referred to as the IC "die", contains embedded electronic circuitry that performs, at least in part, the electrical/electronic functions for the particular electronic device wherein the IC chip is used. The IC chip, however, is not an isolated island. It must communicate with other chips in a circuit through an Input/Output (I/O) system of electrical interconnections, or "interconnects". Moreover, the IC chip and its embedded circuitry are delicate, and must therefore be protected in a package that can both carry and protect it. As a result, the major functions of the IC package are: (1) to provide a path for the electrical current that powers the circuits on the chip; (2) to distribute the signals on to and off of the chip; (3) to remove the heat generated by the circuit; and (4) to support and protect the chip from hostile environments.
Integrated circuits are typically housed within a package that is mounted to a printed circuit board (PCB) or printed wiring board (PWB). An integrated circuit substrate is used to connect the IC chip to the PCB. One popular group of packages is the Grid Array package, which consists of an IC substrate for mounting and interconnecting the IC chip to the electronic package such as a printed circuit board. On the top surface of the IC substrate, an IC chip is mounted and electrically connected to traces that are formed on the top surface of the IC substrate. On the bottom surface of the IC substrate, pins or solder balls are mounted in an array pattern for connection of the electronic package.
The IC chip is typically attached in the center of the IC substrate. Wires are used to connect a plurality of contact pads on the IC chip to lands on the IC substrate. The lands are typically the ends of the traces nearest the IC chip. The lands are in turn connected to the array of pins or balls on the opposite surface on the IC substrate by holes (also known as "vias") through the IC substrate.
The substrate can be made from different materials such as ceramic, plastic or tape. This invention focuses on the tape substrate. The tape substrate, commonly called tape automated bonding (TAB), is used to wire IC chips when extreme package thinness is required, such as in a credit card size radio. Various methods are used to form the TAB that are known in the art. One type of package is a tape ball grid array (TBGA) package 10, shown in FIG. 1, that consists of a tape substrate 35 with metal circuitry etched on a top surface creating traces 15, typically made of copper, interconnecting the IC chip 20 and the solder balls 25. Holes 30 are formed in the tape substrate 35 material for attaching the solder balls 25 to the traces 15. Wire bonding 40 is used to connect the IC chip pads to the traces 15 and the assembly is encapsulated with plastic encapsulant 45 for protection. Disadvantageously, handling the TBGA package during assembly is very difficult due to the thinness of the package and the flexibility of the tape substrate 35.
Another disadvantage with the TBGA package 10 is that it is very poor at heat dissipation. There is no thermally conductive metal structure attached to the IC chip 20 to dissipate the heat generated by the IC chip 20. An optional heatspreader 50 may be attached to the TBGA package 10 to dissipate heat, as shown in FIG. 1. The heatspreader 50 typically comprises a planar thermally-conductive element, such as a sheet of metal, that is located above the IC chip 20 and attached to it by the encapsulant 45. Thus, heat generated in the IC chip 20 by operation of the circuits embedded therein is conducted through the encapsulant 45 to the heatspreader 50, where it is dissipated, thereby helping maintain the junction temperatures of the semiconductor devices included within the circuits of the IC chip 20 at safe operating levels. Disadvantageously, this method is not thermally efficient because the encapsulant does not conduct heat efficiently. The heatspreader also adds cost and increases the thickness of the TBGA package.
In view of the above, it is evident that what is needed is a support structure for a tape ball grid array (TBGA) package that can be used during assembly for ease of handling and will also improve the thermal performance of the package by efficiently dissipating heat generated by the IC chip.